The present invention relates to an indwelling needle assembly to be used for fluid infusion, hemodialysis, and the like. More specifically, the present invention relates to a safety indwelling needle provided with a safety mechanism.
In recent years, a risk of transmission of AIDS, hepatitis virus or the like to medical personnel caused by accidental puncture by a pointed edge of an injection needle or the like, contaminated by blood has been emerging as a problem. Therefore, a safety indwelling needle for an indwelling needle assembly having an inner needle and an outer needle, which prevents accidental puncture by covering an inner needle after use without putting a cap again thereon, has been invented. For example, there is disclosed a safety indwelling needle in which an inner needle is retracted and stored in a needle cover with a spring by pressing a button provided on the indwelling needle after puncture (for example, Japanese Patent Laid-Open No. 52499/1998).
Also, there is disclosed a safety indwelling needle in which a spring-type needlepoint protecting means is disposed within an outer needle hub, and when the inner needle is pulled out, the needlepoint protecting means comes apart from the outer needle hub to cover an extremity of the inner needle (for example, Japanese Patent Laid-Open No. 102345/2002).
Furthermore, there is disclosed a safety indwelling needle characterized in that a sliding cover provided on an inner needle is extended and the entire needle is stored therein when the inner needle is pulled out from an outer needle (for example, Japanese Patent No. 3400550 and Japanese Patent Laid-Open No. 148270/1995).
In the safety indwelling needles provided with a safety mechanism in the related art, the needlepoint protecting means for covering the inner needle pulled out from an outer needle unit is required to have a size that affords enough space for accommodating the entire inner needle, and hence the size of the indwelling needle itself is significant. Also, the safety indwelling needle including a spring as a needlepoint protecting means has a problem such that a force required for pulling the inner needle increases because a friction between the inner needle and the needlepoint protecting means increases by an urging force of the spring, whereby the usableness is deteriorated. Also, in the safety indwelling needle having a needlepoint protecting means for storing the entire inner needle by a sliding cover, there is a problem such that shortening of the length of the sliding member in a constricted state is limited, and the structure becomes complicated by shortening the same.